B737 Overhead panel !

[Flight Detent]

Is it still so that the paint colouring of the overhead control panels in the B737 are different shades of grey, not sure which ones, but they are consistant on all models, I'm told.
That is, two different shades of colouring are used.
Anybody know the origin of this system of colouring, and is it still current in the latest models?

Cheers

['%MAC']

There are 5 light gray panels in the B-737, 4 on the overhead; pneumatics, hydraulics, gen bus, and fuel, and the engine instruments on the center panel. These are all items that will require timely action in the event of an engine failure:

Boeing 737 Engine Failure Checklist
Thrust Lever....................................................... ..............Close
Start Lever....................................................... ................Cutoff
Engine Fire Warning Switch...............................................Pull
If fire warning light remains illuminated:
Engine Fire Warning Switch.......................................Rotate L or R
If after 30 seconds the fire warning light remains illuminated
Engine Fire Warning Switch.......................................Rotate to remaining bottle
If fire warning light remains illuminated:
Land at nearest suitable airport

Isolation Valve Switch...................................................... ..Close (pneumatic panel)
APU Bleed Air Switch...................................................... ..Off (pneumatic panel)
APU (if available).................................................. ......Start (dark gray) & on bus (gen bus panel)
Note: if both generator busses are not powered, the galleys and one system B hydraulic pump are not powered. (hydraulics panel)

Fuel........................................................ ..........................Balance (fuel panel)
If wing anti-ice is required:
Pack Switch (affected side).............................................Off (pneumatics panel )
Isolation Valve Switch.....................................................A uto (pneumatics panel)
do not open the isolation valve unless fire has been extinguished.
Accomplish the one engine inoperative landing checklist when appropriate.


But what this leaves out is the APU start panel, that's dark gray, right below the Gen Bus panel - go figure...